The new paper examines 15 previous studies of more than 800,000 people living in Europe, North America, South America, and Asia. Researchers from University College London combined the data and found that people who had never wed were 42 percent more likely to develop dementia than married folks. Also, widows and widowers were 20 percent more likely to experience this serious mental decline than people who still had living spouses.

Though marriage and a lower risk of dementia is just a link and not a proven cause-and-effect, the researchers pointed out that married people are likelier to have daily social interaction than those who remain single — which can help the former maintain their everyday functions. Also, marriage is associated with less risk of harmful lifestyle habits. But if a married person has lost his or her spouse, grieving the death can increase stress levels, which can potentially affect the brain and cause problems with cognitive ability.

On a somewhat lighter note, an accompanying editorial by researchers from the National University of Singapore and the Chinese University of Hong Kong explained that having sex has been linked to better cognitive function — and married people may be having more sex than those who aren't hitched.

That said, it's worthwhile to keep in mind that the researchers cautioned that this new research does not mean that dementia is now easily preventable. There are many other dementia risk factors that make some people more likely to develop the disease than others. That's why they want research to continue focusing on how to prevent it from happening in the first place.

We couldn't agree more — and we think this review is a promising and fascinating start.